Users of public restroom facilities often desire that all of the fixtures in the restroom operate automatically without being touched by the user's hands. This desire is generally due to the increased user awareness of the degree to which germs and bacteria may be transmitted from one person to another in a public restroom environment. As a result, many public restrooms are being transitioned to “hands-free” or “no-touch” restrooms, where all of the fixtures, including toilet and urinal units, hand washing faucets, soap dispensers, towel dispensers and door opening mechanisms, are automatic and operate without being touched by a user. It is believed by many users that hands-free or no-touch public restroom facilities reduces the opportunity for transmission of viruses and bacteria which may result from contact with fixtures in a public restroom.
In office buildings and other similar upscale buildings, the building owner or manager many times wants to offer upscale public restroom facilities to match the buildings décor. One way the building owner or manager can provide an upscale public restroom is to provide in-counter soap dispensers, rather than wall mounted units or on-counter dispensers. In-counter soap dispensers generally have a dispensing nozzle above the counter. Typically, in-counter soap dispensers have a reservoir, which holds the soap, and pump to move the soap from the reservoir to the nozzle. The reservoir and pump are generally mounted underneath the counter. In-counter soap dispensers are known in the art. See, for example, U.S. Pat. Nos. 6,142,342, 6,467,651 and U.S. Patent Application Publication US200910166381 A1. These dispensers deliver an essentially uniform amount of soap on each attenuation of the pump located in the dispenser.
Foam soaps in recent years are gaining in popularity. Generally, foam soaps are stored in a reservoir as a liquid until the time of dispensing. At the time of dispensing, a foam pump pumps the liquid from the reservoir and the pump converts the liquid to foam. Foam soaps tend to be much easier to spread than a corresponding liquid soaps. In addition, foam soaps result in less waste of the soap due to splashing or run-off the users hand since foam soaps typically have much higher surface tension than liquid soaps. Generally, foam soaps give the user a perception of having more soap available to wash their hands than an equivalent weight of a liquid soap. That is, a sufficient amount of a liquid soap to wash a users hand may give the user a perception that there is an insufficient amount of soap to complete the hand washing event. Many times, the user will seek one or more additional doses of liquid soap to complete the hand washing event, if the user perceives the amount of soap dispensed is insufficient to complete the hand washing event. As a result, dispensers which dispense foam soaps tend to provide more hand washings, on a liquid volume basis of the soap in a reservoir, as compared to dispensers which dispense liquid soaps.
In-counter foam soap dispensers are generally of two types. One is a pressurized system which generates the foam at the nozzle. A second type is a non-pressurized system. Pressurized systems are expensive to install and maintain. Non-pressurized systems typically generate the foam under the counter and send the foam to an outlet of the nozzle via a tube. A certain amount of the foam soap remains in the tube until the next use. However, foams tend to collapse overtime and return to a liquid form. This process is called liquefaction. When liquefaction of the foam soap occurs, the dispenser may not dispense a sufficient quantity of the foam soap to effectively clean the hands of the user. Non-pressurized systems have the advantage of a lower initial cost and a lower maintenance cost.
One way to deal with liquefaction is to dispense more foam soap than is needed to clean the user's hands. However, providing too much soap to the user requires the user to use more water to effectively remove the soap from the user's hands. This can result in a waste of water and soap. Wasting water and soap on each hand washing event can result in an increase cost to the building owner in building operation.
Another issue in the art is fluid dispensers which have dispensing tubes which are relatively long may experience fluid loss in the dispensing tube during period of non-use. This can be caused by many different factors, including, for example, evaporation of the fluid, leaking of the fluid from the dispensing tube among other reasons. As a result, a dispenser having a delivery tube may not dispense a sufficient amount of a fluid, in particular a hand cleaning fluid to effectively clean a user's hands.
There is a need in the art for a non-pressurized hands-free foam soap dispenser that effectively will dispense a sufficient amount of foam soap, even if the liquefaction or collapse of the foam soap occurs between uses of the dispenser. In addition there is a need in the art for a fluid dispenser which will always provide a user with sufficient fluid to clean a user's hand during a hand washing event.